Web driving system with driving, braking and motion sensing units adjacent each margin of the web



June 6, 1967 H. EPSTEIN ETAL 3,323,700

WEB DRIVING SYSTEM WITH DRIVING. BRAKING AND MOTION SENSING UNITS ADJACENT EACH MARGIN OF THE WEB Filed June 22, 1965 4 Sheets-Sheet 1 F ig. I

INVENTORS HERMAN EP'STElN WILUAM P. FOSTER ATT OR NEY June 6, 1967 H. EPSTEIN ETAL 3,323,700

WEB DRIVING SYSTEM WITH DRIVING. BRAKING AND MOTION SENSING UNITS ADJACENT EACH MARGIN OF THE WEB Filed June 22, 1965 4 Sheets-Sheet 2 Fig. 3

INVENTORS HERMAN EP$TE\N W\LL\AM P. FOSTER ATTORNEY June 6, 1967 H. EPSTEIN ETAL 3,323,700

WEB DRIVING SYSTEM WITH DRIVINS BRAKING AND MOTION SENSING UNITS ADJACENT EACH MARGIN OF THE WEB INVENTORS HERMAN EPSTE\N BY W\LL.\AM P. FOSTER ATTORN EY June 6, 96 H. EPSTEIN ETAL 3,323,700

WEB DRIVING SYSTEM WITH DRIVIN", BRAKING AND MOTION SENSING UNITS ADJACENT EACH MARGIN OF THE WEB Filed June 22, 1965 4 Sheets-Sheet 4 KMJJOK $02 a.

m 5 mrm m? w m RL EL m ATTORNEY United States Patent 3,323,700 WEB DRIVING SYSTEM WITH DRIVING, BRAK- ING AND MOTION SENSING UNITS ADJACENT EACH MARGIN OF THE WEE Herman Epstein, Philadelphia, and William P. Foster,

Paoli, Pa., assignors to Borg-Warner Corporation, Chicago, ill, a corporation of Illinois Filed .l'nne 22, 1965, Ser. No. 465,867 1'2 Claims. (Cl. 226-47) The present invention is directed to a system for displacing a web, and more particularly to such a system which operates to sense the effective rates of displacement of each edge portion of the web and selectively regulate driving and braking of each edge of the web to maintain the appropriate alignment across the width of the web.

Various systems for regulating the rapid displacement of a continuous web from a supply roll are known. One environment in which such systems are used is a highspeed page printer of the type utilized in connection with computer systems for provinding a visual output representation of information processed by such computer. With many known systems a mechanical printing arrangement has been utilized to imprint the output information on a paper web, but this utilization of mechanical elements which must be physically displaced from and returned to their starting positions for each information imprint imposes a limitation on the system operating speed. If significant advances in the speed of information print-out from such high speed units is to be realized, it appears that a non-mechanical printing arrangement must be employed. One such arrangement for realizing high speed print-out of information in a page format is an electrostatic printing system in which the information is initially placed on the web by selectively charging discrete Web areas to form a latent image, thereafter inking or rendering the latent image visible by passing the web adjacent opaque particles which are attracted to the selectively charged areas, and subsequently fixing the temporarily visible image to provide a permanent record.

As improved systems have been built to move a paper web at the speed required to afford a significant improvement over mechanical printing systems, the problem of maintaining the web properly aligned has grown proportionally. Various systems previously devised for the textile or other fields to minimize skew of a cloth web traveling along a straight path do not overcome the control problems encountered in the high-speed page printer field. To effect a high-speed print-out, it is necessary not only to provide exact control of paper web displacement at high speed in a continuous or slewing operation, but also to provide a selective or stepping type of paper displacement in which the web is incrementally displaced through a short distance and stopped prior to the next incremental displacement.

Accordingly the present invention is particularly directed to the controlling of a paper web for displacement at high speed in a page-printing operation to afford both continuous or slewing control and incremental or stepping control as desired. Although the invention finds particular utility in such an arrangement, those skilled in the art will appreciate its ready adaptation to related systems.

In a preferred embodiment, the present invention comprises a pair of sensing means, one disposed adjacent each edge of the paper web, to sense passage of regularly spaced indicia provided on the marginal portions of the web and to provide electrical signals related to the rate of web movement. Drive means and brake means are provided to regulate the starting and stopping of the web. Of particular importance to the invention is the provision ice of a novel control circuit for receiving the electrical signals from the pair of sensing means, and for regulating the displacement of the web as a function of the electrical signals and of a received command signal to provide displacement of Web along its path without any Thisalignment across the width thereof.

To acquaint those skilled in the art with the best mode contemplated for making and using the invention, a preferred embodiment will be described in connection with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:

FIGURE 1 is a perspective illustration depicting components of the inventive combination for sensing web displacement and regulating displacement and braking of the web;

FIGURE 2 is a side view of one element of the combination depicted generally in FIGURE 1;

FIGURE 3 is a side view of a portion of a page-printing arrangement in which the novel drive arrangement of the invention finds utility;

FIGURE 4 is a simplified block diagram useful in understanding the operation of the control circuit of the inventive combination; and

FIGURE 5 is a block diagram depicting the control circuit of FIGURE 4 in more detail.

General description of the invention In FIGURE 1 paper Web ill is shown incorporated in the novel drive system of the invention for displacement as indicated by the arrows 11. Each marginal portion of the Web, which may be anywhere between the center and extremity of the web, defines or includes a plurality of regularly spaced apart indicia. In this embodiment such indicia comprise a series of apertures 12 along the lefthand margin and another series of apertures 13 along the right-hand marginal portion. These apertures may have other utility such as providing for mating engagement with teeth of drive sprockets along other portions of the novel page printer in which the system is incorporated, but for purposes of describing the instant invention, apertures 12 and 13 may be considered indicia or reference marks, and it will be apparent that symbols or indicators could also be positioned on the web for the same punposes.

Adjacent the left portion of the Web is a first brake assembly 14, and a second brake assembly 15 is disposed adjacent the right-hand portion. The print or selective charging station 16 incldes an endless metallic stencil l7 journalled on a pair of indexing pulleys 18 and 20. The stencil 17 defines information-denoting apertures which, when passed in selective registration with charge-producing means (not shown) behind the web are effective to provide the requisite latent image on the web.

The first sensing means 21 is shown adjacent the left margin of the web 10, and a similar detecting means or mark-detecting assembly 22 is indicated at the right marginal portion. The web It} is changed in direction of travel through about 90 as it passes over a central roller 23 freely journalled on a support shaft 24-. Near the left hand margin of Web 10 and outwardly of central portion 23, a separate shaft portion 25 supports a timing disc or pinwheel 26. Shaft portion 25 is journalled for free r-otation and is not coupled to central shaft 23. Pinwheel an is apertured near its outer portion to provide two separate sets or arrays of timing apertures. One array is nearer the center of the timing disc and includes apertures spaced apart on a circle by a given angular increment, and the outer array of apertures is spaced on a different radius relative to the center of the pinwheel and these apertures are spaced from each other by an angular increment or interval which is different from that of the inner set of apertures. The illuminating means or lamp 27 is disposed adjacent one side of the pinwheel for passing light through both the inner and outer aperture arrays. On the other side of the pinwheel, a first photosensitive means 28 is positioned to provide electrical signals over a conductor 3t) responsive to receipt of light through the apertures in the outer array of the pinwheel, and as each inner aperture passes between lamp 27 and a lower photocell 31, a related electrical signal is provided over output conductor 32. Thus, for a given linear displacement of the web 10, two different sets of electrical timing or sync signals, occurring at different frequencies, are provided over conductors 30 and 32. It is again emphasized that shaft 25, which supports timing disc 26, is journalled independently of central roller 23 so that the angular displacement of pinwheel 26 is dependent only upon the rate of displacement of paper web 10.

In an analogous manner, adjacent the right margin of web 10 another lamp 33 is positioned to pass light through inner and outer radially displaced sets of timing apertures in a second pinwheel 34, for receipt in one of the two photosensitive units 35 and 36, having corresponding output conductors 37 and 38, respectively. Reference unit 34 is supported on a shaft portion 40 which, like the other shaft portion 25, is journalled independently of the center roller 23. Shaft 40 supports a plurality of teeth 41 spaced apart at intervals related to the spacing between apertures 13 along the right margin of the web. It is this engagement of teeth 41 in apertures 13 that effects displacement of pinwheel 34 as a function of the rate of movement of the right margin of web 10, thus to provide the electrical timing signals over conductors 3'7, 38 in timed relation to the movement of the margin of the paper web. Similarly teeth 42 are provided at the corresponding intervals along the edge of shaft 25 for receipt within apertures 12 at the left margin of the paper. While these arrangements of sensing means 21 and 22 have proved positive-acting and very effective in translating the paper web marginal displacement rates into two series of electrical timing signals, many variations of this basic arrangement are possible. For example, the lamps 27, 33 could be arranged to pass light directly through apertures 12, 13 along the margins of the paper for sensing by the respective photocell units without the intervention of timing discs or pinwheels. Another alternative is the provision of spaced-apart marks upon the periphery of the paper web, with the lamps and photosensors placed on the same side of the web and the photocells adjusted to sense variations in the level of the light reflected from the web as the indicia pass the point of maximum illumination by the lamp.

In the upper portion of FIGURE 1, two separate drive units 43, 44 are shown. Each of these units is positioned to engage a marginal portion of web It) and, responsive to receipt of drive signals, to effect displacement of the web edge. Drive assembly 43 comprises a capstan roller 45 supported from and continuously driven (when the system is energized) over a shaft 46. On the other side of the left edge of web It) is a pinch roller 47 journalled on the end of a lever 48. Bias means depicted as a spring 50 is provided and connected to lever arm 48 to urge roller 47 toward capstan 45 with a force only sufficient to secure the paper between the pinch roller and the capstan roller, which force is not sufficient to impart a driving force to the paper edge. A solenoid or other actuator 51 is shown mechanically coupled over an arm 52 to lever 48. The solenoid has an input conductor 53 for receiving electrical signals to effect operation of solenoid 51 and displacement of pinch roller 47 toward the capstan roller 45 with a force sufficient to effect displacement of paper Web It) in the direction shown by the arrows.

Brake assembly 14 comprises a magnetic circuit in the interior thereof (not shown) for actuation upon receipt of a signal over input conductor 55 to provide an electromotive force which attracts the movable portion 56 of the brake supported on the other side of the paper from the base unit 54, thereby gripping the edge of the paper web tightly and halting the left margin of the paper. Support leg 57 is provided for affixing to the support cabinet (not shown) of the printer, and the spring unit 58 is coupled both to support leg 57 and to the movable shoe 56 of the brake assembly. Spring 58 is initially deformed to urge shoe 56 toward base unit 54 wit-h a force sufiicient to retain the edge of the paper in the brake assembly 14, but a force which will not retard movement of the paper. Such driving and braking assemblies are now well known in the art, and no further explanation thereof is necessary to a full understanding of the present invention.

In FIGURE 2 timing disc 26 is shown in more detail, including its support on shaft 25 and mounting on the support shaft 24. Teeth 4,2 are provided on the freely-journalled shaft 25 to engage the corresponding holes in the edge of the paper web. The outer apertures of the reference unit or timing disc are referenced by 97, and the apertures in the inner circle, or those nearer the center of the timing disc, are numbered 98. With a different angular spacing of the two sets of apertures near the margin of pinwheel 26, it is evident that two different sets of timing signals can be provided for one displacement of the paper through the printing station. By selectively energizing either one or another of the photocells adjacent the two different arrays of apertures, one of the two different sets of timing signals can be selected to provide an appropriate number of lines per inch on the printed form. It is manifest that two different lamps could be provided and their illumination directed through the two different arrays of apertures, to impinge on the sensitive portion of a single photosensor diode so that selective energizati-on of one or another of the lamps would give the desired variations in the electrical signal rate. The precise means of providing the difference in timing of these control signals is not important but it is useful to have the selection in the number of timing signals provided for a given incremental displacement of the paper.

In FIGURE 3 the passage of paper web 10 through the print station of the invention under regulation by the novel control arrangement of this invention is indicated. Looking toward the left edge of the paper, brake assembly 14 is shown with the reference numerals utilized indicating specific portions of the brake assembly in FIG- URE 1. In FIGURE 3 a base unit 54 of the brake assembly is shown affixed to a support plate 60 by a pair of fastening screws 61 and in like manner the support arm 57 is fixed by a pair of support screws 62 to base 60. The path of paper web 10 is upwardly through brake 14, over anvil electrode 63 adjacent the printing" stencil 17, with the stencil or metallic mask 17 being retained between adjacent portions 64, 65 of an air-bearing assembly, shown secured by a pair of mounting screws 66. The anvil member 63 is secured by a fastening screw 67 to an outer 'U-shaped support portion 68, and this entire assembly is journalled on a shaft 70 to permit the anvil assembly to be rotated about shaft 70 away from the stencil element 17 during the loading operation of the page printer.

After leaving the vicinity of the anvil and metallic stencil the paper is displaced upwardly to the left, around shaft portion 25 as previously indicated in FIGURE 1. This movement of the paper displaces pinwheel 26. and the paper is displaced to the right past drive unit 43, whence it falls downwardly to begin the formation of a buffer loop between the printing station and the next unit of the page printer.

Control circuit: general description As shown in FIGURE 4, the novel control circuit of the present invention comprises a first control stage or left control flip-flop 101, for sending the go and stop signals to the left drive assembly 43 and the left brake assembly 14, respectively; a second control stage, or right control flip-lop 102, for selectively applying go and stop commands to the right drive unit 44 and brake assembly a start circuit 203 for correlating a command signal with status signals related to synchronizing (sync) information derived from the indicia along the left and right marginal portions of the web to issue a start signal responsive to the appropriate correlation between the command and status signals; and a delayed stop circuit 204, useful in eflecting a reset of either of the left and right control flip-flops from the driving to the braking condition if it attempts to drive one side of the paper and it appears from the sync signals that the other marginal portion of the web is not being driven or that one of the sync indicia has been missed. In addition a pair of and circuits 156 and 130 are shown in FIGURE 4 to assist in applying the delayed stop signal to the Hipflops 101 and 102.

Each of the left and right control stages has a pair of output terminals designated as the l and 0 connections. When either of these stages provides a signal of high level at one of the output terminals, the level at the other output terminals is low. In much of the data processing equipment these conditions are produced by providing a signal level of approximately 13 volts positive for the high level signal and a signal close to zero volts or ground for the low level signal. Thus by way of explanation, if the signal level at the 1 output terminal of stage 101 is high, then the signal level at the 0 terminal is low. The high level signal is applied over conductor 126 as a go signal which effects energization of pinch roller solenoid 51 to commence driving the left margin of the web. Simultaneously a low level signal is applied over conduetor 137 and is not effective to actuate the brake assembly 14 so that no retarding force is applied by this assembly. At the same time a high level signal is applied over conductor 150, the driving assembly 44 is also energized and the paper web 10 is driven through the system.

Assuming that the equipment is initially in a stop p0sition with a high level signal at the 0 output terminals of both control flip-flops 101 and 102, then a low level signal is present at each of the 1 output terminals and on conductors 126 and 150. The low level signal from conductor 126 is applied over conductors 128, 135 to the upper input terminal of start circuit 203 (as will become apparent from the more detailed showing of FIG- URE 5, conductor 128 is actually connected in a slightly different arrangement but for the general illustrative purposes of FIGURE 4 this showing is adequate). The low level output signal on conductor 150 is translated over conductors 149, 160 to the lowermost input terminal of start circuit 203. The supplying of the two low-level signals to the upper and lower input terminals of start circuit 203 is analogous to the application of status or information signals which inform circuit 203 of the instantaneous output conditions of left and right control stages 101, 102. A command signal to drive the paper through the system is then provided by applying a third low level signal over conductor 171 to the input side of start circuit 203, which issues an output or start signal over 173 and applies this signal to the upper input terminal of each of the left and right control flip-flops 101, 102. This start signal changes the state of each flip-flop, providing a high level output signal at the 1 terminal and the signal level at the 0 terminal immediately goes low. Accordingly the brakes are released and the pinch rollers engage the capstan rollers to drive paper through the system.

It is noted that as soon as the signals at the 1 output terminals went to the high level, the low level signals denoting the status of stages 101, 102 were removed from the uppermost and lowermost input connections of start circuit 203. Accordingly the start circuit will not be effective to issue another start command over conductor 178, notwithstanding the subsequent continuous provision of a control or command signal over conductor 171, until both of the left and right control stages have been reset to provide high level output signals at their 0 terminals and low level signals at their 1 terminals.

As the paper web is displaced through a linear distance corresponding to the angular displacement between two adjacent apertures in pinwheel 2.6, the next aperture comes into registration along a line between lamp 2'7 and photosensor 28 (assuming that 28, rather than photosensor 31, is in the circuit at this time). An output pulse is provided over conductor 30 by this action and it is this sync pulse or electrical timing signal, denominated the left sync signal in FIGURE 4, which is applied over conductor to the central input terminal of fli flop 101, resetting this stage and providing a low level output signal at the 1 terminal and a high level signal at the 0 terminal. This low level signal at the 1 terminal is immediately translated as a status signal over conductors 126, 123, and to the upper input connection of start circuit 203 but inasmuch as the requisite low level signal is not yet supplied over conductor 160 to the lowermost input terminal of circuit 203, there is still no start signal issued over conductor 178.

Had the right marginal web been displaced through a distance corresponding to the displacement of the left margin, a related electrical signal would have been issued over conductor 37 for providing a right sync signal over conductor 116 to reset stage 102, thus providing a low level signal at the 1 output terminal and a high level signal at the 0 output terminal, and thus providing the requisite third low level signal over conductors 150, 149, and 160 to cause start circuit 203 to issue an output pulse. When the system of the invention is in the continuous driving or slewing mode of operation, this just-described operation occurs so rapidly that with a control signal continuously applied over conductor 171, the two additional status signals are applied over the other two input conductors of start circuit 203 (signifying the equal linear dis placement of each side of the web) before the high level signals on conductors 137, 161 have actually had a chance to set the brakes 14, 1 5 and halt the paper movement. For purposes of the present explanation, it is assumed that although the appropriate left sync signal has been delivered over conductor 115, for some reason there is no provision of a corresponding right sync signal over conductor 116.

With control flip-flop 1101 providing a high level signal over conductor 137 to energize the left side brake solenoid, this high level signal is also applied over conductors 1411, 144 to the uppermost input terminal of delayed stop circuit 204. This stop circuit is effective when a pair of high level signals are received over the upper two input terminals or over the lower two input terminals, to wait for a predetermined delay time and then issue a low level signal over conductors 188, 187 which signal is applied to the lower input terminal of circuit 156 and the upper input terminal of circuit 130. Because the right sync signal has not been received, a high level signal is still present on conductor and this signal is applied over conductor 149 to the second input terminal of delayed stop circuit 204 to initiate operation of this circuit. During the delay time, before the low level signal is issued over conductor 188, the fact that the left side brake has already been set and the right side drive means is energized is continually indicated by the application of the low level signal from conductor 126 over conductors 128, 135, and 133 to the lower input terminal of stage 130. At the expiration of the time delay period, another low level signal is provided over conductors 188, 107 to the other input terminal of stage 130, to apply a signal over conductor 131 to the lower input terminal of right control flip-flop to reset this stage, providing a high level signal at the 0 output terminal and a low level signal at the 1 output terminal. Thus the brake at the right side will be set and the driving signal removed from the pinch roller solenoid at the right side of the paper web. Accordingly if the sensing means at either marginal portion of the web misses the aperture or there is some other inadvertent operation of the system, a delayed stop signal (analogous to supplying a. substitute sync signal from the side of the paper which missed the signal) is automatically provided from delayed stop circuit 204.

With this general view of the main components of the novel control circuit a more detailed explanation will not be set forth.

Control circuit: Specific arrangement As shown in FIGURE 5, lamps 27 and 33 are con nected in parallel across conductors 103, 104, between which a suitable energizing potential difference is applied. With the lamps illuminated and paper being displaced to rotate the pinwheels 26, 34, light impinges on each of the four photosensors 28, 31, 35 and 36 to provide sync or electrical timing signals. To determine which electrical timing signals are utilized, a line-spacing switch is provided, which may include a relay 106 for receiving control signals over conductor 107, or a simple mechanical switch may be used to displace both movable contacts 108, 110 from one to another position. In the positions indicated, contact 108 engages fixed contact 111 and contact 110 engages fixed contact 112; these movable con tacts are displaceable to engage fixed contacts 113, 114, respectively. In the illustrated position of switch 105, sync signals from photosensor 28 are provided by light impinging thereon after passing from lamp 27 through the outer array of apertures in pinwheel 26, for translation over conductor 30, contacts 111, 108 and conductor 115 to left control flip-flop 101. Simultaneously light energy passes from lamp 33 through the apertures of the outer circular array in pinwheel 34 to impinge on photosensor 35, producing electrical signals which are passed over conductor 37, contacts 112, 110 and conductor 116 to the right control flip-flop 102.

A margin hole counting circuit is provided in this embodirnent and circuit simplification is obtained by taking advantage of particular design constants. There is an integral number of aperture intervals on disc 34, associated with each margin hole pin interval on the shaft 40. This is true for both outer and inner aperture arrays. The two integral numbers have no common factor. More specifically, there are shown in FIGURE 2 four aperture intervals in the outer array of apertures 97 and three aperture intervals on the inner array of apertures 98 in the angular space required for one margin hole pin interval. Because of the relationship described above, outer and inner apertures have a common radial alignment at, and only at, angular intervals corresponding to margin hole spacing, the distance between two successive web apertures. By selecting only the sync signals which are coincident at both outer and inner photosensors on one margin, a train of pulses is obtained which provides one pulse for each margin hole. Sync pulse selection is accomplished by amplifiers 117, 118 and the and gate 124 (FIGURE 4). The and gate may be considered as part of the circuit means for providing an output signal (over conductor 125) only in response to simultaneous occurrence of tim ing signals over both conductors 120, 121, which is analogous to providing an output signal each time one of the web indicia passes a reference point.

Output conductor 37 of photosensor 35 is coupled not only to contact 112 but also over conductor 120 to the input side of amplifier 118. In like manner the output terminal of photosensor 36 is coupled over conductors 38, 121 to amplifier 117. The small circular symbol shown at the tip or output point of amplifiers 117, 118 is a wellknown symbol for an inversion of the signal passed from that stage. Accordingly, the signals from amplifiers 117,

118 are inverted, passed over respective conductors 122 and 123, again inverted in the input circuit of and stage 124, and passed over conductor 125 to a suitable cumulation circuit (not shown) for providing a total of the number of holes or indicia sensed along the margin of the web. This information is useful in determining the length of the web which is displaced past a reference point, such as a page cut-otf point where a blade is actuated to sever the web into page increments.

Returning to the left control flip-flop 101 in the upper central portion of FIGURE 5, the 1 output terminal is coupled over conductor 126, amplifier 127, and conductor 53 to solenoid 51, to activate the pinch roller at the left side of the web when a high level signal is provided at the 1 output terminal of left flip-flop 101. The 1 output terminal of stage 101 is also coupled over conductor 128 to the lower input terminal of nor stage 130, the output terminal of which is coupled over the conductor 131 to one side of capacitor 132, the other side of which is connected to ground, and conductor 131 is also coupled to the lower input terminal of right control fiip-flop 102. The 1 Output terminal of left control stage 101 is also coupled over conductors 128, 133 to the upper input terminal of nor stage 134 and, over another conductor 135, to the upper input terminal of another nor stage 136.

The 0 output terminal of left control stage 101 is coupled over conductor 137, amplifier 138, and conductor 55 to solenoid for actuating the brake assembly 14 (FIG- URE 1) at the left-hand side of the paper web. The 0 output terminal is also coupled over conductors 141, 142 in the upper input terminal of another nor stage 143. The same terminal is also coupled over conductors 141, 144 to the upper input terminal of another nor stage 145, the output circuit of which is coupled over conductor 146 to the upper input circuit of another nor circuit 147. The output circuit of stage 136 is coupled over conductor 148 to the lower input terminal of stage 147.

Considering the right control stage 102, the 1 output terminal is coupled over conductor 150, amplifier 151, and conductor 152 to pinch roller solenoid 153 of the drive means at the right-hand portion of the paper web. Another output circuit from the same terminal extends over conductors 150, 154 and 155 to the upper input terminal of nor stage 156, the output terminal of which is coupled over conductor 157 to the lower input terminal of left control flip-flop 101. Conductor 157 is also coupled through capacitor 158 to a plane of reference potential, conventionally designated ground. The 1 output terminal of flip-flop 102 is also coupled over conductors 150, 154 and 160 to the lowermost input terminal of stage 134, and over conductors 150, 149 to the lower input terminal of stage 145.

Considering now the 0 output terminal of right flip-flop 102, this terminal is coupled over conductor 161, amplifier 162, and conductor 163 to the solenoid 164 for actuating the brake assembly at the right-hand portion of the paper web. The same 0 output terminal is also coupled over conductors 161, 165 to the lower input terminal of nor stage 136, and the same 0 terminal is coupled over conductors 161, 165 and 166 to the lower input terminal of nor stage 143.

The go or feed paper command signals are received at either of the two input terminals of nor stage 167 over one of input conductors 168, 170. The output connection from this stage is extended over conductor 171 to the central input terminal of nor stage 134. The out put connection from stage 134 extends over conductor 172 to the upper input terminal of a similar stage 173, the output terminal of which is coupled over conductor 174 to the uppermost input terminal of another nor stage 175. The output terminal of stage 175 is coupled over conductors 176, 177 to the lower input terminal of stage 173 to provide a latching signal upon operation of stage 175. The same output terminal from stage 175 is 9 also coupled over conductors 176, 178, and 180 to the upper input terminal of right control stage 102, and over conductors 176, 178, and 181 to the upper input terminal of left control stage 101.

Near the lower left-hand portion of FIGURE is a switch or relay 182 for sensing the extent of tape in a buffer loop between adjacent stations of the page printer system and, when the loop reaches or exceeds a maximum level, this relay is operated to displace movable contact 183 to engage fixed contact 104, shown connected to a means for providing a positive potential. Upon such actuation this positive potential or high signal is passed over contacts 184, 133 and conductor 185 to the central input terminal of stage 175. A bypass resistor 186 is coupled between conductor 185 and ground.

Considering the left and right control stages 101, 102, the top-most connections are shown coupled directly to ground. The lower central connections of each are coupled in common over a conductor 187, which also is coupled to the lower input terminal of stage 156 and the upper input terminal of stage 130. Conductor 187 is also coupled over conductor 1 88 to the output connection of stage 190 in delayed stop circuit 204.

From the output point of stage 147 there are two separate circuit connections. The first extends through a capacitor 191 to an amplifier 192, and a resistor 193 is coupled between a point to which positive potential is applied and the common connection between capacitor 191 and amplifier 192. The output connection from the amplifier 192 is coupled over conductor 194 to the lower input terminal of nor stage 195, the other input terminal of which is coupled over conductor 196 to the output connection of stage 147. The output connection from stage 195 is extended over conductor 197 to the input side of inverter 190.

Control circuit: operation It is preferable in commencing an explanation of the novel control circuit, to start at a point in time when the 0 output signal level is high at each of the left and right flip-flops 101, 102, providing signals to the solenoids 140, 164 which energize the brake assemblies 14, in PI- URE 1 and securely grip the paper web at each edge. With the 0 outputs in the high condition, the '1 outputs are low and there is no signal to the pinch roller solenoids 51, 153 and no tendency to drive the paper. With no paper movement, the pinwheels are stationary and there is no sync signal being provided from any of the photosensors to the center of either of the left and right control flipflops 101, 102. The low level signals from the 1 output terminals are applied to the upper and lower input terminals of stage 134, to provide status signals for start circuit 203, as previously described.

The control or commence-feed signals can be applied to the start circuit over either of conductors 160, 170. For example, a command signal can be continuously applied over conductor 170 when it is desired to slew or continuously drive paper through the system. Conductor 168 may be connected to a selective switching or stepping arrangement (not shown) which can be utilized in the thread or load position of the equipment to periodically energize the system and step the paper until the desired operating point or starting point is reached.

Assuming that a high level signal is now provided over either of conductors 168, 170, the signal is inverted in stage 167 to pass a low-level signal over conductor 171 to the center input terminal of stage 134. In that low-level signals were already present at the upper and lower input terminals of stage 134, the signal level at conductor 172 goes from the low to the high level.

This signal transition is reversed in stage 173 so that at conductor 174 the signal level goes from high to low and is applied to the upper input terminal of stage 175, which already has low level signals present at the other two input terminals (from stage 143 and from conductor 185, resistor 186, to ground). Accordingly, the signal level on conductor 176 immediately goes from a low to a high level providing the start command to the upper left input terminals of each of the left and right control flip-flops 101, 102. Concomitantly a latching signal is provided over conductors 176, 177 to the lower input terminal of stage 173.

Receipt of the start signal drives the 1 output terminal of each control stage to the high level condition, applying energizing signals to the pinch roller solenoids 51, 153 over previously described circuits to urge the pinch rollers against the capstan rollers and commence driving the web. Simultaneously the 0 output terminal of each flipfiop 101, 102 provides a low-level signal to effect a deenergization of the brake solenoids 140, 164, permitting the brake assemblies to pass the paper web toward the pinw-heels as the pinch rollers commence driving the paper.

As the 1 output terminals provide the high-level signals for energizing the respective pinch roller solenoids, the same high-level signals are applied to the uppermost and lowermost input terminals of stage 134, to return the output level of this stage to the low level and provide a high-level output signal from stage 173. Concomitantly the low-level output signals from the 0 terminals of each of the left and right flip-flops 101, 102 are applied to the respective terminals of stage 14 3 and these low-level signals drive the output signal from stage 143 to a high level, which signal is applied to stage 175 and changes its output signal to the high level. Thus the output signal on conductor 176 is driven back from the high to the low level. It is apparent that the start command circuit, including stages 134, 173, 143 and 175, is automatically reset every time a start command is issued through the left and right control flip-flops 101, 102. The application of this low-level signal from start circuit 203 over conductors 176, 178, 100, and 181 to the upper input terminals of the left and right control stages 101, 102 does not reset the flip-flops.

Responsive to energization of the respective pinch roller solenoids, the paper web is displaced as indicated by arrows 11 in FIGURE 1. As was done in connection with the simplified circuit of FIGURE 4, it is assumed that the left marginal portion of the web is displaced faster than the right edge and that under these conditions a control or sync signal is provided from photosensor 20 over conductor 30, contacts .111, 108 and conductor 115, to the middle input terminal of left control flip-flop 101. The time duration or the pulse width of this sync signal is related to the physical width of the slot and the rate of angular displacement of the timing disc. To achieve a more positive operation, it is desirable in a preferred embodiment to actuate the control flip-flops when the trailing edge of the timing aperture passes, that is, upon receipt of the trailing edge of the sync pulse rather than the leading edge. A suitable flip-flop control circuit will be identified hereinafter for use as units 101, 102. In reality this unit functions as a flip-flop within a flip-flop, which in a sense remembers when the leading edge has been received and provides the desired actuation upon receipt of the trailing edge of the sync pulse.

As the trailing edge of the pulse is applied over conductor to the central input terminal of flip-flop 101, the output conditions reverse and the high-level signal is passed from 0 output terminal over conductor 13"], amplifier 138, and conductor 55 to actuate the brake solenoid and set the brake at the left portion of the web. Simultaneously the signal level at the 1 output terminal goes low and the pinch roller at the left side of the web is disengaged. It is still assumed that no signal impulse has been received by photosensor 35 at the right side of the web and that therefore pinch roller solenoid 153 is still energized and the right brake solenoid 16-1 is still deenergized.

As the signal at the output terminal of left flip-flop 101 went high, this high-level signal was translated over conductors 141, 144 to the upper input terminal of stage 145, Which is also receiving a high-level signal from the 1 output terminal of right control flip-flop 102 over conductors 150, 149. Accordingly a low-level signal is provided on conductor 146 and applied to the upper input terminal of stage 147.

Simultaneously a low-level signal is applied from the 1 output terminal of flip-flop 101 over conductors 128, 133, and 135 to the upper input terminal of stage 136. Another low level input signal is provided at the lower input terminal of this stage from the 0 output terminal of flipflop 102 over conductors 161, 165. Thus with these two low-level input signals, a high-level output signal is provided at conductor 148 and applied to the lower input terminal of stage 147. As soon as this signal is provided, a low-level output signal is applied from the output side of stage 147 to the left side of capacitor 191, which allows this capacitor to discharge and effectively turn off stage 192 for a time period of approximately one millisecond. Of course this time duration can be varied to suit the timing needs of the specific circuits. The normally low output condition at conductor 194 thereupon goes to a high level and remains for this time duration, applying a like input pulse to the lower input terminal of stage 195. At the input side of stage 195, the signal applied over conductor 196 went to a low level whereas the signal applied over conductor 194 went to a high level, so that at the output side of stage 115 a signal appears which has a waveform showing a very short-duration spike, with the signal level then remaining low until the termination of the one millisecond time delay interval, at which time the output signal level again goes high. This signal is in effect inverted in stage 1911 so that the resultant output signal over conductor 188 starts from the high level, has a short spike in the negative-going direction (the effect of which is overcome by capacitors 132, 158), but remains high for the time delay interval, and thereafter goes low again. This signal is applied over conductor 187 to the lower input connection of stage 156 and to the upper input connection of stage 130.

When the brake was set at the left margin of the tape as the 0 terminal of flip-flop 101 provided a high-level signal, the 1 output terminal applied a low-level signal over conductor 128 to the lower input terminal of stage 130. After the elapse of the delay time, the low-level signal is provided by circuit 204 and passed over conductors 188 and 187 to the other input terminal of stage 130. Responsive to the concomitant provision of these two lowlevel signals, the level of the output signal at conductor 131 goes high, and this signal is applied to the lower input terminal of right control flip-flop. This action resets flipfiop 102 and provides a high level output signal at the 0 terminal, which is passed over conductor 161, amplifier 162, and conductor 163 to energize brake solenoid 164 and set the brake at the right side of the paper web. It is noted that the same action could have occurred upon passage of light from lamp 33 through one aperture in disc 34, providing an electrical signal in photosensor 35 for passage over conductors 37, 116 to the center input terminal of right control flip-flop 1112, to reset flip-flop 102 and provide the high level output signals at the 0 terminal. At the same time the signal at the 1 terminal goes to the low level, and this low level is passed over conductors 154 and 160 to the lowermost input terminal of stage 134, which has already received the low level output signal from the 1 terminal of left control flip-flop 101 when the brake was set at the left side of the web. Thus if another signal is received from either of input conductors 168, 170 or if the go signal has been maintained during this interval in which the paper has been displaced and the brake circuits again energized, the start command circuit 203 can again provide a start signal as previously described.

Summary The present invention provides for precise, correlated control of the driving system for a wide paper web which finds particular use in a page-printing system. The effective control is realized by sensing the precise increments of displacement along each marginal portion of the Web, and selectively driving and braking the edge portions of the web to provide an overall rapid displacement with each side of the web maintained in proper alignment. A significant measure of the improvement resides in the novel and unobvious control circuit which is efiective to translate each successive command signal only upon detecting sync signals denoting equal displacement at each edge of the web. This action occurs so rapidly within the electronic switching circuitry that when the paper web is continuously driven any stepping or incremental displacement of the paper is not noticeable. Alternatively if desired successive pulse signals can be applied over the input circuit to step the paper and provide incremental displacement.

To assist those skilled in the art in making and using the invention, the flip-flops utilized as the left and right control elements 1131, 102 may be of the type SU32OK, commercially available from the Signetics Corporation in Sunnyvale, Calif. Each of the other logic stages indicated in the drawing, including stages 117, 118, 124, 130, 134, 136, 14 3, 14-5, 147, 156, 173, 175, 190, 192, may be of type SU315K available from the same corporation. Other logic elements are readily usable so long as the described relationships are maintained.

While only a particular embodiment of the invention has been described and illustrated, it is apparent that modifications and alterations may be made therein. It is therefore the intention in the appended claims to cover all such modifications and alterations as may fall within the true spirit and scope of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A system for regulating the displacement of a web having reference marks spaced along each edge of the web, comprising:

first and second mark-detecting means, one disposed adjacent each edge of the web, operable as the web is displaced to detect the passage of said marks and provide electrical timing signals related to the rates of movement of each edge of the web;

drive means disposed to move the web;

brake means disposed to halt the web; and

a control circuit, connected to regulate the selective energization and the de-energization of the drive means and the brake means as a function both of control signals and of the electrical timing signals to maintain proper alignment of the web as it is started and stopped.

2. A system for regulating the displacement of a web having symbols spaced along each margin of the web, comprising:

first and second sensing means, one disposed adjacent each margin of the web, operable as the web is dis placed to provide sync signals related in time to the passage of said symbols;

first and second drive means, one disposed adjacent each margin of the web for driving the web;

brake means positioned to stop the web; and

a control circuit connected to regulate the selective energization and the de-energization of the first and second drive means and of the brake means as a function both of received command signals and sync signals, thus to maintain the desired orientation of the web as it is driven and stopped.

3. A system for regulating the displacement of a web having indicia spaced adjacent each edge portion of the web, comprising:

first and second sensing means, one disposed adjacent each edge portion of the web, operable to provide sync signals as said indicia are displaced past the sensing means;

first and second drive means, one disposed adjacent each edge portion of the web, operable as energized to drive each edge portion of said web independently of the other edge portion;

first and second brake means, one disposed adjacent each edge portion of the web, operable as energized to retard the advance of each edge portion of the web independently of the other edge portion; and a control circuit, connected to regulate the selective energization and the de-energization of each of said first and second drive means and each of said first and second brake means as a function of both said sync signals and of control signals signifying the desired extent of paper displacement. 4. A system for regulating the displacement of a web having interval-connoting symbols near each edge of the web, comprising:

first and second detecting means, one disposed adjacent each edge of the web, for detecting passage of said symbols and providing electrical timing signals related to the rate of movement of each web edge;

first and second drive means, one disposed adjacent each edge of the web, operable to selectively drive each edge of the Web;

first and second brake means, one disposed adjacent each edge of the web, operable to selectively stop the advance of each edge of the web; and

a control circuit, connected to regulate the selective energization and the de-energization of each of said,

first and second drive means and each of said first and second brake means in accordance with receipt of said electrical timing signals and of command signals.

5. A system for regulating the displacement of a paper web having apertures regularly spaced near each margin of the web, comprising:

first and second sensing means, one disposed adjacent each edge portion of the web, each including illuminating means and photosensor means operable upon receipt of light through one of said apertures to provide sync signals related to the rate of movement of each Web margin;

first and second drive means, one disposed adjacent each margin of the Web, operable to selectively drive each margin of the web;

first and second brake means, one disposed adjacent each margin of the Web, operable to selectively halt the advance of each margin of the web; and

a control circuit, connected to regulate the selective energization and the de-energization of each of said first and second drive means and each of said first and second brake means in relation to received control signals and to said sync signals.

6. A system for regulating the displacement of a Web having indicia spaced adjacent each edge portion of the web, comprising:

first and second detecting means, one disposed adjacent each edge portion of the web, operable to detect passage of said indicia and provide sync signals related to the rate of movement of the web edge portions;

first and second drive means, one disposed adjacent each edge portion of the web, operable as energized to drive each edge portion of the web independently of the other edge portion;

first and second brake means, one disposed adjacent each edge portion of the web, operable as energized to retard the advance of each edge portion of the web independently of the other edge portion; and

a control circuit, including a first control stage connected to regulate energization and de-energization of the first drive means and the first brake means along one edge portion of the web, a second control stage connected to regulate energization and deenergization of the second drive means and the second brake means along the other edge portion of the web, means for applying said sync signals to said first and second control stages, and a start circuit, connected for operation in accordance with command signals received over a first input circuit and status signals received over a second input circuit denoting receipt of the sync signals by the first and second control stages, for providing a start signal to said control stages for energizing the first and second drive means at each side of the web.

7. A system as set forth in claim 6 in which each of the first and second control stages is a flip-flop circuit having a pair of output terminals and operable so that when the signal level at either of the pair of output terminals is high the signal level at the other of said terminals is low, with circuit means for applying the signal from one output terminal of a given stage to regulate the drive means at one side of the web and for applying the signal from the other output terminal of the given stage to regulate the brake means at said one side of the web, thereby insuring that both the drive means and the brake means at one side of the web cannot be simultaneously energized.

8. A system as set forth in claim 6 and further comprising a delayed stop circuit operable to provide an output signal at the expiration of a predetermined delay period when either of said control stages passes a stop signal to the brake means at one side of the web while the other control stage is still applying a go signal to the drive means at the opposite side of the web, and circuit means for utilizing said output signal to reset said other control stage, removing the go signal and applying a stop signal to the brake means at said opposite side of the web.

9. A system for regulating the displacement of a web having indicia spaced along each marginal portion of the web, comprising:

first and second sensing means, one disposed adjacent each edge portion of the web, operable upon displacement of the web to sense the passage of said indicia and provide sets of electrical timing signals at different frequencies responsive to displacement of the web at a given speed;

first and second drive means, one disposed adjacent each marginal portion of the web, operable to drive each marginal portion of the web independently of the other marginal portion; first and second brake means, one disposed adjacent each marginal portion of the web, operable to retard the advance of each marginal portion of the web independently of the other marginal portion;

switching means, coupled to said sensing means, for selecting a set of said electrical timing signals at one of said different frequencies; and

a control circuit, connected to regulate the selective energization and the de-energization of each of said first and second drive means and each of said first and second brake means as a function of command signals and of the selected set of electrical timing signals.

10. A system for regulating the displacement of a paper web having apertures regularly defined near each margin of the web comprising:

first and second sensing means, one disposed adjacent each edge portion of the web, each including a reference unit disposed for displacement at a rate proportional to the speed of the web and defining first and second arrays of apertures, each array having a predetermined interval between apertures which is different from the interval of the other array, means for directing light energy to pass through both ap- 15 erture arrays, first photosensitive means for receiving light energy passing through apertures in the first array to provide a first set of sync signals ocpaper web having apertures regularly defined near each margin of the web, comprising:

first and second sensing means, one disposed adjacent curring at a first frequency, and a second photosensitive means for receiving light energy passlng through apertures in the second array to provide a second set of sync signals occurring at a second frequency;

first and second drive means, one disposed adjacent first and second brake means, one disposed adjacent each marginal portion of the web, operable to retard the advance of each marginal portion of the web independently of the other marginal portion;

each edge portion of the web, each including a timing disc disposed for angular displacement at a rate proportional to the linear speed of the web and defineach margin of the web, operable to drive each maring outer and inner arrays of apertures, each array gin independently of the other margin; having a predetermined interval between apertures first and second brake means, one disposed adjacent which is different from the angular interval of the each margin of the web, operable to retard the adother array but which is so related to the interval Vance of each margin of the web independently of spacing of the other array that a common radial the other margin; alignment between apertures in the outer and inner switch means, coupled to said first and second photoarrays occurs only at angular intervals correpondsensitive means, for selecting one of said first and ing to the distance between two successive web second sets of sync signals; and apertures, means for directing light energy to pass a control circuit, connected to regulate the selective through both aperture arrays, and first and second energization and the de-energization of each of said photosensitive means for receiving light energy passfirst and second drive means and each of said first ing respectively through apertures in the outer and and second brake means in relation to received coninner arrays to provide first and second sets of sync trol signals and to the set of sync signals selected by signals occurring at different frequencies; said switch means. first and second drive means, one disposed adjacent 11. A system for regulating the displacement of a h margin of the web, operable to drive each marweb having indicia spaced along each marginal portion gin independently of the other margin; of the Web comprising: first and second brake means, one disposed adjacent first and second sensing means, one disposed adjacent each margin of the Web, operable to retard the adeach edge portion of the web, operable upon dis- Vance of each margin of the web independently of the placement of the Web to sense the passage of said other margin; indicia and provide sets of electrical timing i circuit means, coupled to said first and second photonals at different frequencies responsive to displace- Sensitive means, including an and Circuit f r P ment of the web at a given speed, with the different d g an output pulse only upon simultaneous ocsignal sets providing signals in exact time coincicurrence of a signal in each of said first and second dence as each of the web indicia passes a reference sets of sync signals; and point; a control circuit, connected to regulate the selective first and second drive means, one disposed adjace t energization and the de-energization of each of said each marginal portion of the Web, operable to driv first and second drive means and each of said first each marginal portion of the web independently of and second brake means in relation to received the other marginal portion; control signals and to one set of the sync signals.

References Cited UNITED STATES PATENTS circuit means, coupled to said sensing means, for pro- Sig 226 17 'd t t c I 1 Vl ing an on pu Slgl'l'll on y in response to simul 2,947057 8/1960 Meagher et a1 226*17 X taneous occurrence of a signal in each of said sets of electrical timing signals and;

a control circuit, connected to regulate the selective energization and the de-energization of each of said first and second dripe means and each of said first M. HENSON WOOD, ]R., Primary Examiner.

ALLEN N. KNOWLES, Examiner. 

1. A SYSTEM FOR REGULATING THE DISPLACEMENT OF A WEB HAVING REFERENCE MARKS SPACED ALONG EACH EDGE OF THE WEB, COMPRISING: FIRST AND SECOND MARK-DETECTING MEANS, ONE DISPOSED ADJACENT EACH EDGE OF THE WEB, OPERABLE AS THE WEB IS DISPLACED TO DETECT THE PASSAGE OF SAID MARKS AND PROVIDE ELECTRICAL TIMING SIGNALS RELATED TO THE RATES OF MOVEMENT OF EACH EDGE OF THE WEB; DRIVE MEANS DISPOSED TO MOVE THE WEB; BRAKE MEANS DISPOSED TO HALT THE WEB; AND A CONTROL CIRCUIT, CONNECTED TO REGULATE THE SELECTIVE ENERGIZATION AND THE DE-ENERGIZATION OF THE DRIVE MEANS AND THE BRAKE MEANS AS A FUNCTION BOTH OF CONTROL SIGNALS AND OF THE ELECTRICAL TIMING SIGNALS TO MAINTAIN PROPER ALIGNMENT OF THE WEB AS IT IS STARTED AND STOPPED. 